Alkyl-1, 1-dihaloalkyllead compounds



United States Patent Ofice 3,393,216 Patented July 16, 1968 ABSTRACT OFTHE DISCLOSURE Compounds represented by the following formula wherein Ris an alkyl radical containing from 1 to about carbon atoms, X is ahalogen, R is an alkyl radical containing from 1 to about 3 carbon atomsand n is an integer from 1 to 4 are adaptable for use as antiknockagents in gasoline.

This invention relates to novel compositions of matter. Moreparticularly, this invention concerns organometallic compositionsadaptable for use as antiknock agents in gasolines. This invention isalso directed toward a fuel composition adapted for use in internalcombustion engmes.

It is known that when organometallic compounds such as tetraethylleadand tetramethyllead are employed as antiknock agents for internalcombustion engine, fuel means must be provided to remove thelead-containing products f combustion. At present the most widely knownmethod of removing the lead products is to add to the fuel, in additionto the antiknock agent, certain organic halogen compounds and inparticular organic chlorides and bromides. These organic halides reactin the combustion chamber to form volatile lead halides which areremoved from the combustion chamber during the exhaust cycle. Thisprocess has been called scavenging and material capable of so reactingis referred to as a lead scavenger, or more simply, as a scavenger.

Of the scavengers known heretofore, only ethylene dibromide and ethylenedichloride have been in successful commercial use for many years.Although they have generally met the requirements of good scavengers,they are not completely satisfactory for some conditions of operation ofthe present-day internal combustion engines, especially those engineswhich are used in heavy duty service. Over a period of years the desirefor higher engine output has caused modifications in engine designwhich, for example, have caused a change in the distribution pattern ofthe antiknock and scavengers among the individual cylinders of enginesat intake manifold pressures. It has been found that ethylene dibromideand ethylene dichloride are not completely satisfactory under someoperating conditions in meeting the requirements imposed by thesechanges in engine design. This problem of the disproportionatevolatilities of the antiknock agent and the scavengers has beenrecognized in the art and methods have been offered for its solution,for instance, in U.S. Patents 2,479,900; 2,479,901; 2,479,902; and2,479,903.

It is an object of this invention to provide a novel composition ofmatter adaptable for use as an antiknock agent and fuels containingthese compositions which do not incur this maldistribution problem. Inother words, the compounds and fuel compositions of this invention willcontain an alkyllead antiknock agent and at least the theoretical amountof halogen to scavenge all of the lead employed without incurring anyproblem at all with respect to disproportionate volatilities.

The objects of this invention are accomplished by the provision of novelorganometallic compounds, and fuels containing these compounds, thecompound being described by the following formula:

wherein R is an alkyl radical containing from 1 to about 5 carbon atoms,R is an alkyl radical containing from 1 to about 3 carbon atoms, X is ahalogen, and n is an integer from 1 to 4.

The compositions of this invention are sometimes referred to herein asalkyl-1,l-dihaloalkyllead compounds. The unique feature of thisinvention being the presence, in an alkyllead compound a radical havingthe following formula:

wherein R, X and m are defined as above. Thus, for instance, the termtrimethyl-l,l-dichloropropyl lead refers to a compound having thefollowing formula: a CH3?bCCl2OH-OH3 Likewise the terminology oftriethyl-Ll-dihalOethyl lead refers to a compound having the structuralformula:

A compound referred to as diethyl-di(1,1-dichlorobutyl) lead is thecompound having the formula:

In the composition of this invention the halogen substituents, X, may bethe same or they may be different. Chlorine and bromine are the highlypreferred halogens. Compounds containing both chlorine and bromine inthe molecule are preferred embodiments of this invention. R is an alkylradical having 1 to about 5 carbon atoms. Preferably R contains from 1to about 3 carbon atoms. These radicals may be the same or different, itbeing intended that mixed organoleads come within the scope of thisinvention. It is preferable that R is an alkyl group having from 1 to 2carbon atoms.

A preferred embodiment of this invention is a compound described by theformula wherein R and X are as hereinabove defined.

In the engine fuel compositions of this invention this type of compoundis added to the fuel in amounts corresponding to up to about 6 grams oflead per gallon of gasoline. The exact quantity added to any gasolinedepends largely on the grade of gasoline desired.

The advantages incurred by this invention are:

(1) An antiknock compound containing at least one theory of halogenbuilt into the molecule.

(2) The provision of an antiknock-scavenging composition in which noproblems of disproportionate volatilities between the antiknock and thescavengers are incurred.

(3) That no separate blending of antiknock and scavenger is necessary.

(4) The halogens are bonded directly to carbon and thus the organiccharacter of the compound is maintained as distinguished from the casewhere the lead atom is bonded directly to the halogen and behaves inmany instances like an inorganic salt.

(5) The compounds are hydrolytioally stable.

(6) The rate of decomposition of the scavenging moiety is closelyrelated to the decomposition of the organolead compound and thus therewill be a supply of hydrogen halide available for reaction with the leadcompounds shortly after they have performed their function asantiknocks.

The compounds of this invention are synthesized by cont-acting atetraalkylle'ad compound with any suitable system which generatesdihalocarbene. These systems may be a haloform such as chloroform,bromoform and the like or the trihalo acetates. These compounds aresubjected to the action of materials such as sodium methoxide, potassiumtertiary butoxide, and the like. In order that those skilled in the artmay better understand the compounds and fuel compositions of thisinvention the following examples are given.

EXAMPLE I This example is demonstrative of a method of preparing theorganolead compounds of this invention.

5 parts by volume tetraethyl lead is charged to a reaction vesselcontaining 20 parts by weight sodium ethoxide. 40 parts by volumechloroform is added dropwise while stirring over a period of 2 hours.The reaction is allowed to continue for another hour. The reaction isconducted at approximately 100 C. and ambient pressure. The solids areseparated by filtration. The product, triethyl-l,l-dichloropropyl lead,is recovered in good yield.

It is found that the above method is adaptable to the preparation of anyand all of the organolead compositions of this invention. The necessaryreagents are: A haloform such as bromoform, chloroform,dichlorobromoform, or a chlorodibromoform, a strong base such as analkali metal alkoxide or hydroxide, and an organolead compoundcontaining no unsaturated bonds in the organic portion.

The following examples demonstrate the formulation and use of the fuelcompositions of this invention containing the organolead compoundsherein described.

The base fuel used in these formulations is a hydrocarbon fuel boilingin the gasoline boiling range. These fuels have an ASTM (D-86)distillation with an initial boiling point of about 100 F. and a finalboiling point of about 425 F. Preferably the unleaded base fuel has aresearch octane number as determined by the accepted CFR engine testmethod of at least about 75. Also, the base fuel preferably contains atleast 20 percent by volume of aromatic hydrocarbons and less than 30percent by volume of olefinic hydrocarbons. The total parafiin andnaphthene hydrocarbon content may be as much as 80 percent by volume.The more preferred hydrocarbon base fuels are also those which containfrom 20 to 60 percent by volume aromatic hydrocarbons and from to 30percent by volume of olefinic hydrocarbons. Most preferably a gasolinehaving all-around desirable characteristics has a clear research octanenumber of at least 90 and contains about 50 to 60 percent by volume ofparafiin and naphthene hydrocarbons, about 30 to 40 percent aromatichydrocarbons and about to 15 percent olefinic hydrocarbons.

The fuel compositions of this invention contain up to about 6 grams oflead per gallon of fuel and preferably from about 1.0 to about 5.0 gramsof lead per gallon of fuel. Most preferably the compositions containfrom about 2 to about 4 grams of lead per gallon of gasoline.

EXAMPLE II A blend is prepared by adding triethy1-1,1-dichloropropyllead to a commercially available gasoline base stock to form a mixturecontaining 3.17 grams of lead per gallon of gasoline. This fuel contains1 theory of chlorine based on the lead.

EXAMPLE III Blended to a concentration of 1.0 gram of lead per gallon ispentylethyl 1,1 dibromopropyl l chloro-lbromo-propyl lead with a motorgasoline base stock containing by volume 40.2 percent of aromatics, 5.6percent of olefins and 54.2 percent of saturates. This base fuel has aspecific gravity of 53.4 API (according to ASTM Test Procedure D-287), avapor pressure (according to ASTM Test Procedure D-323) of 8.0 p.s.i.,and the following distillation characteristics (according to ASTM TestProcedure D-86): An initial boiling point of 100 F., a 10 percent pointof 146 F., a mid-boiling point of 232 F., a percent point of 331 F., anda final boiling point of 432 F. The finished fuel contains 1.5 theoriesof bromine and 0.5 theory of chlorine.

EXAMPLE IV In this instance the gasoline base stock is composed byvolume of 35.2 percent of aromatics, 25.0 percent of olefins and 39.8percent of saturates. Its gravity is 552 API and its vapor pressure was8.1 p.s.i. It has an initial boiling point of 236 F., a 90 percent pointof 317 F., and a final boiling point of 392 F.Trimethyl-l-bromol-chloroethyl lead is blended with this base fuel to aconcentration of 6.0 grams of lead per gallon. The resultant fuelcontains 0.5 theory of bromine and 0.5 theory of chlorine.

EXAMPLE V A motor fuel containing 5.0 grams of lead per gallon asdimethylethyl-1,1-dichloropropyl lead is prepared from a gasoline basestock composed by volume of 42.5 percent aromatics, 10.8 percent olefinsand 46.7 percent saturates. This fuel has a gravity of 53.5 API, a vaporpressure of 7.9 p.s.i., an initial boiling point of 102 F., a 10 percentpoint of 152 F., a mid-boiling point of 235 F., a 90 percent point of320 F., and a final boiling point of 399 F. This fuel thus contains 1theory of chlorine.

EXAMPLE VI The base fuel used in this instance contains 39.6 volumepercent aromatics, 4.7 volume percent olefins and 55.7 volume percentsaturates. The fuel has a gravity of 548 API and a vapor pressure of 8.4p.s.i. Its distillation characteristics are an initial boiling point of100 F., a 10 percent point of 139 F., a mid-boiling point of 225 F., a90 percent point of 318 F., and a final boiling point of 420 F. Blendedwith this fuel is tetra-1,1-dichloroethyl lead in amount such that thereare 2.0 grams of lead per gallon. The chlorine content is 4 theories.

EXAMPLE VII Trimethyl-l,l-dibromopropyl lead is admixed with a base fuelcomposed by volume of 36.0 percent aromatics, 7.3 percent olefins and56.7 percent saturates. Other characteristics of this base fuel are:Gravity, 552 API; vapor pressure, 8.5 p.s.i.; initial boiling point ofF.; 10 percent point 137 F.; mid-boiling point 228 F.; 90 percent point327 F.; and a final boiling point of 426 F. On completion of theblending operation, the resultant fuel contains 4.0 grams of lead pergallon.

EXAMPLE VIII Trirnethyl-l,l-dichlorobutyl lead is blended with agasoline composed by volume of 37.5 percent aromatics, 5.1 percentolefins and 57.4 percent saturates. The base fuel has a gravity of 55.3API, a vapor pressure of 8.3 p.s.i., an initial point of 97 F., a 50percent point of 229 F., and a final boiling point of 432 F. Theconcentration of tetramethyllead is adjusted so that the fuel contains3.2 grams of lead per gallon.

5 EXAMPLE 1X Methylethylbutyl-l,l-dichloroethyl lead is blended with agasoline composed by volume of 10 percent aromatics, 45 percent olefinsand 45 percent saturates. The lead concentration is 3.18 grams pergallon.

Other organolead compounds utilized in the fuel compositions of thisinvention are: triethyl-l,1,3-trichl-oro propyl lead;dipropylmethyl-l,l-dibromopropyl lead; terta-1,1-dichloropental lead;methylethyldi-1,1-dichloro- 3-bromopropyl lead;dimethylethyl-l,l-dichloroethyl lead and the like.

The fuel compositions of this invention may contain other componentsbesides these self-scavenging organolead compounds. Such compounds maybe solvents or diluents such as toluene or kerosene or otherhydrocarbons. Dyes may also be present. Also, antioxidants such asalkylated phenols and amines, metal deactivators, phosphorous compounds,other antiknock agents such as tetraalkylleads, amines and metalcarbonyls, antirust and antiicing agents, and wear inhibitors may beadmixed with the compounds of this invention or added to fuelscontaining compounds of this invention.

The organolead compounds of this invention may be used in fuels withoutadditional scavengers. However, if desired, other scavengers may beadded therewith, such as ethylene dichloride and ethylene dibromide ormixtures thereof. The following is an example of such a composition.

EXAMPLE X Trimethyl-1,1-dichloroethyl lead is blended with a gasolinecontaining 55 percent by volume saturates, 36 percent by volumearomatics and 11 percent by volume unsaturates so as to give a leadconcentration of 3.18 grams per gallon of fuel, Together with the leadcompound 0.50 theory of ethylene dichloride and 0.50 theory of ethylenedibromide are added to the fuel.

The foregoing example is repeated in all details except that 1.00 gramof the total lead content is present in the form of tetraethyl lead and2.18 grams is in the form of trimethyl-1,1-dichloropropyl lead. Theamount of added ethylene dichloride and ethylene dibromide mayaccordingly be correspondingly increased, if desired.

What we claim as new and desire to secure by Letters Patent of theUnited States is as follows:

1. A compound represented by the following formula wherein R is an alkylradical containing from 1 to about 5 carbon atoms, X is a halogen, R isan alkyl radical containing from 1 to about 3 carbon atoms and n is aninteger from 1 to 4.

2. The compound of claim 1 wherein R contains from 1 to 3 carbon atoms.

3. The compound of claim 1 wherein X is selected from the groupconsisting of chlorine and bromine.

4. The compound of claim 1 wherein R contains from 1 to about 2 carbonatoms.

5. Trimethyl-1,1-dihaloethyl lead.

6. Triethyl-1,1-dihaloethyl lead.

7. Tripropyl-1,1-dihaloethyl lead.

8. A compound represented by the following formula wherein R is an alkylradical containing from 1 to 3 carbon atoms and X is a halogen selectedfrom the group consisting of chlorine and bromine.

9. The compound of claim 8 wherein R is a methyl group.

10. The compound of claim 8 wherein R is an ethyl group.

11. The compound of claim 8 wherein R is a propyl group.

References Cited Chemical abstracts, vol. 45, pp. 2856-2857 (1951).

TOBIAS E. LEVOW, Primary Examiner.

H. M. S. SNEED, Assistant Examiner.

